The present invention concerns a watch including a movement on which a dial is mounted, and assembled in a casing ring itself mounted in a case including a crystal secured to a bezel, a middle part and a back cover.
In this type of watch, it is often necessary to center and angularly position the crystal and/or the bezel with respect to the dial.
This is the case for example when the crystal or the bezel bear symbols or figures which co-operate with the hands to indicate the time or when the names of towns located in different time zones are marked on the bezel or even when transfers which may be various signs or a trademark are affixed under the crystal.
This is also the case when the watch has a date ring or disc whose figures appear in turn behind an aperture arranged in the dial and when the crystal has a lens for enlarging the figures.
Moreover, if only to allow a time-setting stem of the movement to pass through the middle part and the casing ring, it is also necessary in such watches for the two elements to be properly positioned both angularly and axially in relation to each other.
Very often, the positioning and assembling of the casing ring containing the movement and the various parts of the case are achieved via the middle part, i.e. taking the latter as the reference element, which requires it to have a more or less complicated shape and to be manufactured with precision. Its cost price is thus relatively high.
Moreover, it is quite common for the bezel, middle part and the back cover of the case to be assembled via screws. It is known, for example, to provide in the middle part, on the one hand a first series of holes for screwing on the bezel and on the other hand, a second series of holes for screwing on the back cover. In such conditions, it is not only the cost price of the middle part that is high, but also that of the entire case.